Factor G, a newly discovered dietary agent, is necessary for optimal growth, nitrogen balance, and effective food utilization of animals on purified amino acid diets. Factor G increases the efficiency of food utilization by 30 to 40 per cent. The agent is found in liver, yeast, and other sources. Two forms of the factor, G1 and G2, are found. Objectives of the project are to chemically identify factor G1, obtain it in synthetic form, and study its mode of action, emphasizing its relationship to the utilization of protein, fat and carbohydrate. Likewise, to obtain factor G2 in crystalline form through fractionation and isolation, characterize it chemically, obtain it in synthetic form, and study its mode of action, emphasizing its relationship to the utilization of protein, fat, and carbohydrate. Biological microassay techniques will be developed for both G1 and G2, long term Factor G deficiencies will be studied, the significance of Factor G2 for other species such as mice, guinea pigs, chicks, monkeys, and also man will be investigated, and its effects on protein synthesis, amino acid metabolism, and other aspects of intermediary metabolism will be studied. The effects will be analyzed which are exerted by Factor G on the nutritive value of formula diets for children, purified amino acid rations, and low protein staple foods of underdeveloped countries.